Healthy Food & Healthy Living by Dr. Ayala

Can better hydration help kids think?

How much fluids do you really need?

It’s an old question about one of the most essential components of our diet, yet the answer is surprisingly debatable. Eight glasses a day? To satisfy thirst? So that your urine is clear?

Our body is 60 percent water, and water’s needed for every system and every cell to function. Water keeps our temperature stable, clears waste through our kidneys and urinary system, it pumps blood through our vessels – there’s no function in our body that doesn’t rely on water.

Since water is so critical to bodily functions our body maintains the same blood concentration over wide variations of fluid intake. It’s only when our body is missing significant amounts of water that we’ll see abnormalities in blood tests – and in our ability to function normally.

Dehydration, the state in which water is depleted to the point our body can’t maintain its normal functions is clearly dangerous.

But does being optimally hydrated make a difference? Do smaller variations in fluid intake – the kinds of variations we experience in everyday life and ones that are no way close to clinical dehydration – make a difference?

Although blood samples show little variation in concentration across wide differences of fluid intake, our urine becomes more and more concentrated the less fluid we have – that’s why urine might be a better marker of hydration. Studying urine samples suggests that half the kids in the US have highly concentrated urine, which suggests they’re not drinking much.

Mild fluid deficits, do they matter?

What are the health implications of milder fluid deficits?

A few studies suggest that mild dehydration affects short-term memory in school-aged kids, and on the other hand, when kids are given plenty of water, their memory and attention improves.

A new study, led by Naiman Khan and published in the Journal of Nutrition tests the effect of hydration on cognitive performance. 75 kids aged 9-11 years from Illinois were tested in three conditions for 4 days each: They were drinking as usual (no intervention), were prescribed low water intake (16 oz. a day or about 2 glasses), or high water intake (84 oz. a day or about 10 glasses). On the fourth day of each condition urine was collected to measure its concentration and cognitive tests were performed to assess performance, thought flexibility and inhibition.

And the results: As expected, urine got less concentrated the more fluids the kids took in. Better hydration, benefited kids' working memory and cognitive flexibility according to the the mental tests.

These findings are consistent with findings from other studies that show better hydration improved exercise ability and cognitive flexibility.

Going back to the data that shows that half the kids have concentrated urine signifying insufficient hydration, this study suggests that increasing fluids may be a simple way to help kids think a little better.

Just add water

Our brain is even more water than the rest of our body: it’s 70 percent water. Missing some of it may affect mood, thinking, memory and overall health.

Mood and attentiveness decline first, and while mild changes in body fluids certainly don’t put kids in danger of dropping blood pressure or shutting off their kidneys, proper hydration can help kids perform best at school.

Giving kids access to clean and safe drinking water – safe water fountains in every school! – and prompting them to drink is a really simple way to make sure studying’s a little bit easier and happier.

Optimal hydration may improve overall wellbeing and clarity of mind, and can be a cost- and calorie-free mental boost.

Hydration tips:

How much: 8 (glasses-a-day) isn’t a magic number – so no need to keep count – but is pretty good approximation for an average person in average conditions. The Institute of Medicine (IOM) doesn’t set exact intakes, but recommends about 91 ounces of total water a day for women, and 125 ounces daily for men – and no upper limit for water. Eight glasses is about 64 ounces, add to that the water in food, and you’re not far off from the IOM recommendations. Water needs depend, of course, on activity level, outdoor temperature etc.

What counts: All fluids count, including coffee, tea, soup and the plenty-of water in fruits and veggies.

Assessing hydration: One should rarely feel thirsty, and your urine should be almost colorless. 

Drink More: Provided you’re healthy, your kidneys know how to take care of your fluid levels. Drinking too little can lead to headaches, dehydration, constipation and maybe crankiness, while extra fluids are simply excreted through your urine – it’s difficult to overdrink. Only in unusual circumstances – such as extreme endurance exertion while overdrinking water – can drinking too much water become a problem for healthy people.

Dr. Ayala

 

Full disclosure: I co-founded Herbal Water, which makes organic herb-infused waters that have zero calories and no sugar or artificial ingredients. I’m also a pediatrician and have been promoting good nutrition and healthy lifestyle for many years.

Is soda bad for your brain? How about diet soda?

Soda ads feature young, vibrant, clear-eyed, athletic people. It has already been proven that in fact, soda is actually associated with the opposite: obesity and a myriad of chronic diseases that are the stark contrast of athleticism.

And now, researchers from Boston University, led by Matthew Pase, have shown that it may also dull your mind. It is already known from animal studies that excess sugar leads to Alzheimer’s findings in mice brain tissue. Its effect on human brains hasn’t been examined extensively until now.

The researchers used data from the Framingham Heart Study – a large cohort that is followed every 2 years for decades.

In the first study, published in Alzheimer’s & Dementia, more than 4200 people with different levels of soda intake underwent neuropsychological assessment as well as MRI scans. And the results: The more sugary drinks the participants had, the lower their brain volume and the poorer their memory scores – these findings are consistent with early Alzheimer’s. This held true even after adjustments for diabetes, smoking, exercise and weight.

How about diet soda?

The second study, just published in Stroke examined the connection between sugary and artificially sweetened drinks in almost 3000 people for stroke and in about 1500 for dementia. The volunteers were followed for about 10 years.

It found that diet soda was associated with both stroke and dementia. This was true after adjustment for age, education, smoking, caloric intake and physical activity.

This isn’t the first time diet soda has been correlated with stroke: The Nurses Health Study and the Health Professionals follow-up study both found that diet soda was correlated with stroke. This new study for the first time implicated diet soda with dementia.

Bottom line

Although association, as shown in these studies, isn’t definitive proof – yet – that soda is detrimental to our your brain, there certainly is absolutely no upside to drinking soda, regular or diet.

Sugar is a clear target for reduction in the latest Dietary Guidelines for Americans, and there’s no better place to start than your drinks. Drinking your added sugar it the worst possible way to consume it, as sugary drinks do not lead to satiety, go in unnoticed, at a really fast rate, and cause spikes in blood sugar and insulin.

The motivation to change habits differs from person to person, for some a warning that soda will ruin your figure is powerful, for others, hearing about the risk of diabetes is scarier.

For me, there’s nothing as alarming as the risk of losing my mental capacity.

These new studies offer yet another finding that can help convince people to rethink the way they drink.

Dr. Ayala

Can diet soda lead to weight gain?

Artificial sweeteners were designed to keep food and drinks’ sweet taste while doing away with excess sugar’s unwanted effects, such as weight gain, diabetes and metabolic syndrome.

Sweet tasting drinks without calories seemed like a win-win.

And off we went on this large-scale experiment, which sounded quite promising. But our body is a very complex machine, and simple calorie counts fail to predict what food inventions will do in our body, especially in the long run.

Obesity rates continued to rise, and studies started to indicate that diet soda might not assist with weight loss.

What was even more alarming was the emergence of evidence showing a connection between the consumption of diet soda and metabolic syndrome and type 2 diabetes; another study showed that people who drank diet soft drinks on a daily basis were at increased risk of stroke, heart attack, and vascular death.

These counterintuitive results were a total surprise only to people who don’t appreciate the intricacy of our biology.

Emerging explanations for the diet soda-obesity connection 

Aspartame’s downside

A new study helps explain why diet soda hasn’t yielded the expected weight loss. The researchers, led by Richard Hodin from Massachusetts General Hospital, hydrated mice with aspartame, a sweetener commonly used in diet soda, and compared them to mice that drank plain water. The mice on the aspartame water gained more weight and developed metabolic syndrome.

Further experiments pinpointed the mechanism for weight gain. Aspartame breaks down to phenylalanine in the body, and phenylalanine interferes with intestinal alkaline phosphatase, a beneficial enzyme that helps prevent diabetes and metabolic syndrome.

The researchers demonstrated that when you add intestinal alkaline phosphatase to diet soda and regular soda in a test tube, the activity of this beneficial enzyme was significantly lower in the diet soda solution.

They then looked at the effect of aspartame in the intestine of living mice, and found the same effect inside the body: The mice given aspartame had low activity of intestinal alkaline phosphatase – the ‘good’ enzyme that fights obesity and metabolic syndrome.

Microbiome havoc

Another recent study, led by Eran Elinav, fed mice several commercially available sweeteners (saccharin - Sweet-n Low, sucralose - Splenda, and aspartame - Equal) and found that the mice developed glucose intolerance, a condition that is a forerunner of type 2 diabetes. 

Further tests implicated an altered gut microbial flora as the reason.

When these sweetener-treated mice were given wide spectrum antibiotics the glucose intolerance went away. When the fecal bacteria of the sweetener-treated glucose intolerant mice were transferred to normal mice, they, too, developed glucose intolerance. Furthermore, the gut bacteria that dominated the sweetener-treated mice’s gut are associated with type 2 diabetes in humans, and are involved in digesting and storing carbohydrates.

These are mice studies, though. Is this relevant to people?

The researchers also looked at 381 non-diabetic people, and found that using non-caloric sweeteners was associated with glucose intolerance, high glucose measurements and other signs of the metabolic syndrome. The volunteers that reported using non-caloric sweeteners had the same patterns of altered gut bacteria populations seen in the sweetener-treated mice. 

Lastly, 7 people who don’t usually use non-caloric sweeteners were fed the maximum recommended amount of Sweet-n Low for 7 days. In this very short time 4 of the 7 developed glucose intolerance, and showed alteration in the gut microbial population. When the gut microbes of these 4 people were transferred to mice, those mice developed glucose intolerance, too.

This study shows quite nicely that non-caloric sweeteners can alter gut microbes in mice -- a change that has negative metabolic consequences -- and provides preliminary evidence that it can happen in humans too.

Unexpected consequences

To further appreciate how complicated our handling of diet soda can be, here’s another little example: Our intestine (or bowel) is covered with cells that secrete hormones. These cells react to the presence and composition of food by secreting peptides such as glucagon-like peptide 1 (GLP-1), peptide YY (PYY) and cholecystokinin – these names are not important – that work on the brain, signal satiety and control glucose by influencing the secretion of insulin. Guess what: Artificial sweeteners seem to not affect these hormones the way real food does.

So although at this point we can’t be sure that diet soda directly causes obesity and metabolic syndrome, I think it’s fair to say the experiment isn’t going too well.

These latest studies offer a few fascinating mechanisms that can explain the link between diet soda and untoward outcomes.

An explanation, and perhaps also a lesson.

We have co-evolved with the traditional foods that come from nature; we have survived and thrived on them from the beginning of human time. They combine into endless possibilities – culinary boredom isn’t even a possibility.

As much as I like technology, innovation and progress, food might not be the place to experiment with new materials. Replacing soda, a drink with nothing but empty calories, with a drink equally lacking in nutritional value but with calorie-free sugar substitutes, isn’t likely to advance our wellbeing – both are silly inventions.

Dr. Ayala

Full disclosure: I co-founded Herbal Water, where we make organic herb-infused waters that have zero calories and no sugar or artificial ingredients. I’m also a pediatrician and have been promoting good nutrition and healthy lifestyle for many years.

Soda news: election results, diabetes and the art of misinformation

Election results

Soda taxes were on the ballot in 4 cities on November 8th. The fact that these measures were even there is meaningful: Every time soda is discussed as a public health issue, people are reminded that the evidence tying them to obesity, diabetes and heart disease is piling up. Fifty million dollars were spent on persuasion efforts according to the New York Times, with Big Soda -- opposing the tax -- heavily outspending the tax supporters.

Yet the citizens voted for the tax in all 4 cities; San Francisco, Oakland, Albany CA, and Boulder CO will join Philadelphia and Berkeley, who passed such measures recently.

The anti-soda movement is gathering momentum.

Sugary drinks linked to autoimmune diabetes, too

Sweetened beverages are linked with type 2 diabetes – where typically, the body becomes resistant to insulin.

A new study now finds that drinking soda is also associated with autoimmune diabetes – in which the immune system destroys the pancreatic islet cells that produce insulin, and therefore causes a state in which the body doesn’t produce the critical hormone. The Swedish study, found that 2 drinks of sweetened beverages doubled the risk of latent autoimmune diabetes in adults (LADA) – which is an adult onset autoimmune mediated diabetes, with features similar to type 1 diabetes -- and this was regardless of whether the drinks had caloric or non-caloric sweeteners. And in this study, there was a dose-response relationship: the more sugary drinks, the greater the risk of diabetes.

Industry sponsored confusion

In the face of growing evidence warning us about the harms of sugary drinks the beverage industry fights back by spreading confusion.

A new study in the Annals of Internal Medicine finds that of 60 studies looking at the relationship between soft drinks and obesity, type 2 diabetes, and metabolic syndrome, the majority, and all those that were led by independent researchers found a link. When the study didn’t find a link that study was always conducted by researchers with financial ties to the soft drink industry.

The researchers, from University of California San Francisco, led by Dean Schillinger, warn:

“This industry seems to be manipulating contemporary scientific processes to create controversy and advance their business interests at the expense of the public's health.”

Industry-sponsored studies create the feeling that soda’s harmful effects are controversial, when in fact, pretty much all experts in the field and independent researchers claim otherwise.

Nevertheless, soft drinks are in continuous decline, that, despite ever increasing spending on marketing and soda tax opposition.

Dr. Ayala

Full disclosure: I co-founded Herbal Water, which makes organic herb-infused waters that have zero calories and no sugar or artificial ingredients. I’m also a pediatrician and have been promoting good nutrition and healthy lifestyle for many years.

A simple tip for a more successful school year: Get enough fluids

Is the water bottle your constant companion, or are you the type that trusts we can do just fine in between hydration opportunities? Does hydration status really matter all that much?

Clearly, dehydration is an unhealthy, dangerous state. Even mild dehydration – loss of just 2 percent of body weight in water – makes us less alert, affects our wellbeing, and of course makes us feel thirsty. But going without water for just a few hours hasn’t been studied much up until now.

4 hours without water

A new study, led by David Benton, in the American Journal of Clinical Nutrition, recruited 101 undergraduate students, aged 18-30 years, and put them in a warm (86 °F, 30 °C) room for 4 hours, during which they performed cognitive tests.

Half the students got a 5oz drink of water 90 and 180 minutes into the experiment.

The students were not aware that what was tested was the effect of hydration on cognition – they were told that the experiment was about the effects of heat. The tests, which were repeated 3 times throughout the 4-hour study, included memory recall quizzes -- in which the students were given lists of words, and asked to recall as many as they could remember immediately after, and then again 20 minutes later -- attention tests and subjective mood scores.

Students that didn’t drink water forgot more words in both the immediate and delayed memory recall test, and had poorer attention scores. The students who got some water also reported less anxiety at the end of the test.

The 26 men and 24 women who had no water for 4 hours lost on average 0.72 percent body weight, but at 90 minutes into the experiment the participants lost just 0.22 percent body weight, which is very little. Nevertheless, memory was already affected.

Is your kid drinking enough water at school?

This experiment suggests that even small changes in hydration can make a difference. Mood and alertness are the first to be affected when our body needs food and drink, and while mild changes in body fluids certainly don’t put us in danger of dropping blood pressure or shutting off our kidneys, proper hydration can help a student to perform at his best. Kids also lose a larger proportion of their water due to their smaller size and higher activity levels. The authors cite a few studies that prove that as a first-grader, a drink can help you think, and that 7-9 year olds that got an additional drink performed better on visual attention tasks.

As the school year starts, giving kids access to good drinking water, and reminding them to take that drink is a really simple way to make sure studying’s a little bit easier and happier. Hydration affects mood and if we can buy a little peace of mind with a glass of water lets do it.

By federal law, free drinking water has to be available to students during school meals. In between, kids should have access to plain water throughput the day, but policies change state-to-state and district-to-district.

Does your school have functioning water fountains? Unfortunately, due to old pipes some school fountains have been found to dispense water with unsafe lead levels.

So, as the school and academic year commence, encourage kids to pay attention to hydration, check that they have access to water that has been tested, and set an example by drinking enough yourself.

To a happy and healthy school year!

Dr. Ayala